test/crypto: fix statistics case

test/crypto: fix statistics case

The test case - test_stats is directly accessing the
cryptodev and its dev_ops which are internal to library
and should not be used directly by the application.
However, the test case is also missing to check for the
error ENOTSUP. It should skip the case if the API returns
ENOTSUP. This patch fixes these two issues.

Fixes: 202d375c60bc ("app/test: add cryptodev unit and performance tests")
Cc: stable@dpdk.org
Signed-off-by: Apeksha Gupta <apeksha.gupta@nxp.com>
Acked-by: Akhil Goyal <akhil.goyal@nxp.com>